1. Field of the Invention
The present disclosure relates to a nitride compound semiconductor device and a manufacturing method thereof.
2. Description of the Related Art
Wide band-gap semiconductors represented by group III-V nitride compounds (chemical formula: AlxInyGa1-x-yAsuPvN1-u-v (wherein 0≦x≦1, 0≦y≦1, x+y≦1, 0≦u≦1, 0≦v≦1, and u+v<1)) have high breakdown voltage, good electronic transport property, and good thermal conductivity, and thus are very appealing as a material for high temperature, high power, or high frequency semiconductor devices. Further, in field effect transistors (FETs) having, for example, an AlGaN/GaN heterostructure, two-dimensional electron gas is generated at an interface thereof by the piezoelectric effect. The two-dimensional electron gas has high electron mobility and high carrier density, and is receiving much attention. Moreover, heterojunction FETs (HFETs) using an AlGaN/GaN heterostructure have low on-resistance and fast switching speed and are capable of being operated at high temperature. Consequently, application of integrated circuits such as inverter circuits formed using these nitride compound semiconductors under a high temperature environment or under a high voltage that could not be used before is hoped for (see, for example, Japanese Patent Application Laid-open No. 2009-289956).
Accordingly, use of nitride compound semiconductor devices applied under a high voltage is desired. However, when a high voltage is applied to a nitride compound device, the device may deteriorate and current leakage may occur and leakage current may increase over time.
Accordingly, there is a need to provide a nitride compound semiconductor device with suppressed current leakage and a manufacturing method thereof.